Long term variation of nutrient and phytoplankton in the eastern Yellow Sea

초록

To understand the longterm change of phytoplankton ecology in the Yellow Sea, we analyzed the environmental and phytoplankton data produced in the eastern part of the Yellow Sea from 1987 to 2008. The distribution of water temperature, minimum salinity and transparency (Secchi disc depth) showed slight increases over a 20 year period. The mean concentration of DIN has increased dramatically due to the increasing input of N from land and atmospheric deposition as similar trend in the western Yellow Sea. The increases of silicate and phosphate might be introduced by the increase of precipitation and industrial discharged water. By these increases of DIN, silicate and phosphate, the abundances of phytoplankton showed the distinct increasing trend. The primary productivity of phytoplankton has also increased slightly due to the increase in DIN, transparency and phytoplankton abundances. However averaged chlorophyll a concentration showed the decrease trend in the early of 2000’s and again increase in the recent. The increase of temperature influenced the change of dominant composition of phytoplankton from diatom to dinoflagellates and nanoflagellates during the summer.